Studies Show That the Curveball Isn’t Too Stressful for Young Arms

A youth game in Summit, N.J. New research about youth pitching injuries puts some sports medicine experts in an awkward spot.Credit
Juan Arredondo for The New York Times

For almost as long as children have been throwing baseballs, adults have been telling them about the worst thing they could do to their still-developing arms: throw curves.

The warnings go back to the earliest days of sports medicine, orthopedic surgeons say, at least to the 1950s. In the 1970s, Robert Kerlan, the eminent surgeon who cared for Sandy Koufax, condemned curveballs as murderous on the elbows of professional pitchers, “to say nothing of the young athletes whose bones and joints are still growing.”

That remains the mantra of many sports medicine experts. The orthopedic surgeon James Andrews, who performs more than 100 Tommy John ligament-transplant operations most years, cautions that children should not even think about throwing curves until they are 14.

Are those doctors all alarmists?

Maybe so, according to two studies in which scientists and surgeons evaluated more closely than before the effects of curves on young arms. The studies were done independently by research teams in Connecticut and in Alabama. Each compared the forces across the elbows of pitchers as they fired fastballs and curves. (The Alabama study also included changeups). Each study concluded that curves are less stressful than fastballs and, based on the data collected, contributed little, if at all, to throwing injuries in youth players.

“I don’t think throwing curveballs at any age is the factor that is going to lead to an injury,” said Glenn Fleisig, the chairman of research at the American Sports Medicine Institute in Birmingham, Ala.

Carl Nissen, the principal author of the other curveball study and an orthopedic surgeon at the Connecticut Children’s Medical Center in Farmington, echoed that. “I can comfortably stand up and say the curveball is not the problem,” he said.

The curveball research has not ended the debate. If anything, it seems to have intensified it. One of the reasons is that the findings come from reputable sources and in particular from the A.S.M.I., whose president and founder is Andrews.

Over the years, the institute has produced research studies on all manner of sports movement, from biomechanical comparison of female and male baseball pitchers to an analysis of the swings of professional and amateur golfers. In 2006, Fleisig and Andrews published a study on the effects of curveballs on college pitchers: curves were less stressful on the elbow than fastballs.

Intrigued, the research team repeated the study using youth pitchers as their subjects. They posted notices on youth baseball Web sites seeking players in the Birmingham area for a curveball study. Even that proved somewhat controversial.

“We had a few complaints from coaches saying, ‘How dare A.S.M.I. promote and endorse the curveball,’ ” Fleisig said.

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In all, the institute’s study looked at 29 youth pitchers from ages 9 to 14. All were told to throw their curves — fastballs and changeups, too — as if they were in a real game. The results, published last year in the American Journal of Sports Medicine — Nissen’s study has been accepted for publication in the same journal — were similar to those that Fleisig had found with the college pitchers: Curves were less stressful than fastballs; nothing linked curves to elbow injuries.

Why for so many decades have most doctors and youth coaches believed otherwise? Fleisig said the evidence had been based largely on anecdotes, and that over the years those stories simply began to sound like fact.

“Why did people believe the world was flat? Because one guy told another it was flat and it looked flat. Until someone discovered that it wasn’t,” he said.

The new research has put some sports medicine experts in an awkward spot.

Topping the list is Andrews, a surgeon sought out by dozens of injured professional athletes each year. In July, Andrews became the president of the American Orthopaedic Society for Sports Medicine, a position in which he is championing a national campaign to curb sports injuries in children. Andrews does not challenge A.S.M.I.’s study. But he is hardly trumpeting the findings.

“It may do more harm than good — quote me on that,” Andrews said during an interview in his Birmingham clinic. He fears that parents and coaches may interpret the findings improperly, as a license to teach kids to throw too many curves or begin when they are too young. “There are still some unknown questions,” he said.

Andrews cited several limitations of the study. The fact that it was conducted entirely in a lab also needed to be considered, he said. Under game conditions when youth pitchers are fatigued, Andrews suggested, curves could be dangerous.

“I just operated on one kid this morning,” he said. “At age 12, he tore his ulnar collateral ligament in two. His travel ball coach called 30-something curveballs in a row. He became fatigued. Then he threw one that snapped his elbow.”

Despite differences over curves, experts do agree on other risks to young pitchers. At the top of the list are unreasonably long seasons and pitchers throwing too many innings in individual games. One study of youth pitchers written by Fleisig and Andrews found youth players who pitched more than eight months a year increased their risk of an injury that led to surgery fivefold. Youth players who threw more than 80 pitches a game were four times more likely to need an arm operation than those who did not, according to the study.

“I’m not saying, everyone throw the curveball,” Fleisig said. “I’m saying, if we’re going to prevent injuries, change the focus. We should be looking at overuse.”

Mark Hyman is the author of “Until It Hurts: America’s Obsession With Youth Sports and How It Harms Our Kids.”